A technique (Thermal Flying-height Control, hereinafter “TFC”) is used, in which Joule heat generated by applying a current to a thin-film coil, is used to project a head portion so as to reduce a space between a head (an element region in the head portion) and a disk. However, since a wide area of the head portion is projected in the TFC, it is difficult to selectively project a region (element region) to be desirably the lowest point.
Thermally assisted magnetic recording is advanced in research and development as a technique for improving surface recording density of a magnetic disk drive (as an example of a disk drive). In the thermally assisted magnetic recording, use of near-field light is investigated as an approach to momentarily heating a small write area on a disk. To generate the near-field light, laser light is introduced into a near-field optical element disposed near a write pole of a magnetic head. Laser light that reaches the near-field optical element is partially converted into near-field light and heats a write area on a disk. However, the laser light is largely converted into heat in the near-field optical element, so that a region near the magnetic pole locally projects due to thermal expansion.
In the light of this, it is considered that heat generation in the near-field optical element for thermally assisted magnetic recording is used to project a magnetic head so as to reduce magnetic spacing, as is described in Japanese Patent Publication No. 2007-193906. In a thermally assisted magnetic recording head disclosed in that document, a thermal expansion layer including a material having a high linear expansion coefficient is provided between a magnetic pole and a near-field light generating portion, and heat generated during introducing laser light into the near-field generating portion is used to locally project a magnetic head portion.
However, this approach offers the following problem. Specifically, since laser light during performing thermally assisted magnetic recording is used to generate heat, input into the thermal expansion layer is inevitably synchronized with writing. That is, a projecting distance or projecting timing cannot be optionally controlled. Furthermore, a read element portion cannot be projected in reading.
In short, while a write element portion may be projected by heat generated by a coil in writing, a means for projecting a read element portion is not provided. Moreover, when laser light in thermally assisted magnetic recording is used to generate heat, a projecting distance or projecting timing cannot be optionally controlled.